This invention relates to an apparatus for producing prefabricated concrete and reinforced concrete elements having high dimensional accuracy. More particularly, this invention relates to an apparatus for producing tunnel elements such as the tube shaped elements of subway tunnels which require great dimensional accuracy.
Prefabricated elements used to construct concrete structures, particularly those structures having special fields of application and utilization, e.g. tunnels, must meet stringent strength and dimensional accuracy standards. In order to properly fabricate the elements, the formwork and forms must be constructed so that the elements are fabricated with dimensional accuracy. In addition, a proper insert system must be used which can be placed accurately into the forms during fabrication of the elements so that dimensional accuracy and integrity is assured. Also, the water to cement ratio used in the preparation of the concrete as well as the particle structure of additives must be correct to assure adequate strength of the finished elements. Of course, the working of the concrete into the forms, its setting and removal of the finished element must be controlled so that the finally fabricated element has dimensional accuracy and integrity as well as the required strength. In addition, it is advantageous if the form can be reused to assure that each of the finished concrete elements has the same dimensions, if such is required, thus making it possible to have serial production of substantially identical products.
Typical concrete elements of the type which this invention contemplates are tubing elements for subway tunnels. The subway tunnels are assembled from slice-shaped cylindrical elements which are required to meet stringent strength and dimensional accuracy standards. These standards are much stricter than the conventional standards used in the manufacture of concrete elements which are not intended to be used in structures of the type described herein.
Prefabricated concrete elements used in the construction of elevated and underground buildings are made in forms wherein the roughness coefficient of the surfaces of the forms which shape the surfaces of the concrete elements has an arithmetical mens deviation from the mean line of the profile of generally R.sub.a =20-40 .mu.m. Removal of the finished product from these forms requires at least partial disassembly of the formwork.
The extraordinary dimensional accuracy required for, e.g. tunnels, cannot be assured with the conventional forms which are partially disassembled to remove the finished element, unless very costly and complicated apparatus are used.
There is therefore a need for an apparatus which can be used to fabricate a series of concrete elements with a high degree of dimensional accuracy and reproducability as well as high productivity.
It is a primary object of this invention to provide an apparatus for producing concrete elements of high dimensional accuracy.
It is a further object of this invention to provide an apparatus which can be used to produce a series of dimensionally accurate concrete elements at a highly productive rate.
It is yet another object of this invention to provide an apparatus from which concrete elements produced therein can be removed without disassembling the apparatus while at the same time preserving the removed concrete element's structural and dimensional integrity, e.g. dimensions, corners and edges.
It is yet a further object of this invention to provide a rigid apparatus of undetachable or undismountable construction for the serial production of prefabricated concrete and reinforced concrete elements or formed products of a high dimensional accuracy that do not require cores, said apparatus having rigid form means for the products; means for filling the form means with the concrete and providing vibration to produce the formed products and means for removing the formed products from the form means without disassembling the form means.